#460 AudioEffects - The CANary
Playing with a popular 74HC14 bird chirp effect by Wilf Rigter and making a CANary sculpture.
Here's a quick demo..
The effect is produced by the missing of a couple of Schmitt oscillators running on a 74HC14.
- the primary oscillator is modulated by an LDR
- a secondary oscillator mixes the signal for a piezo speaker
Note that the "HC" series 74HC14 Hex Inverter with Schmitt Trigger Inputs is really required. A 74HC04 without Schmitt Trigger inputs can just about work but is hard to stabilise, and an LS series 74LS14 will not work.
The circuit is optimised for around 3.3V supply. At higher voltages, oscillation can fail.
A quick breadboard build to verify behaviour..
Here's a test on the breadboard..
Wiring it all up on a an old coke can, here is the CANary: